Copying lathe



Aug. 19, 1930.. L. E. TOPHAM COPYING LATHE Filed Feb.- 9, 1928 Patented 'Aug. 19, 1930 s- M UNITED ATATI JS LAURENGEIEQ TOPI-IAM, or WENHAM;"MASSACHUSETTS,"ASSIGNOR TO UivrTnn snon 1 MACHINERY CORPORATION, OF rA'rEnsonnEw JERSEY, A oonronnrronormns SAGHUSETTS COPYING LATHE Applicationiiled February 9,1928 S ri al NO, asaoea a I 7 This invention relates to copying lathes and illustrated as embodiedina last lathei In the ordinary last lathe both the right and leftwlasts are turned from a single right model, the model and block being rotated in the same and inyoppositeidirections, called direct and reverse cutting, respectively,

' in the two cases. F

In order .to secure perfect reproduction of rights and left's it is necessary that, in reverse cutting, where a left is. reproduced from a right model, the model and thelast block be always .reversely and symmetrically situated relatively to the modeliwheel and cutter, In

other words, they must have been rotated at all times equally relatively to the plane con taining their axis of. rotation and the model wheel, and cutter centers, Such a plane has been called the (width), grading plane,

' 2 and will be herein so designated, though there is no question of width grading involved in the present invention. When a'swing frame isused its angular movement is compounded with those of the oppositely rotating model and block, and since the reverse driving mechanism is mountedin the swing frame itself, so that the model and blockrotate equally and oppositely relatively to the swing frame, they :are not rotated equally and oppositely relatively to the grading plane-inall positionsof the swing frame, whichcauses a relative twist in them about their longitudinal axes, which is strongly observable by com'parison of localities'of varying heights, The. problem of direct reproduction involves no difliculty because the model and block maintain the same behavior relatively to the grading plane, and whatever that behavior may be, accurate reproduction will'result. An object of the present invention-is to avoid the aboveedescribed difficultylinthe case of reverse'reproduction.

' Thisis accomplished by providinga swingingmembercarrying the reversing mechanism and having a plane fixed in it whichfis always coincident with the grading plane. Asdisclosed,this member is a secondary swing frame afiordinga second connection between the primary swing frame and the machine,

soconstructed that its connections with the primary swing frame and with the ,Inain frame are at the'same distance from the pivotal axis of the primary swing frame as is the, model wheela'xis. vThis secondary frame carries the transmission gearin vbetween the model and the block and, thereiore, I am en abled to effectequal'rotation ofithe' model and block in opposite'directions relatively to q the grading plane The above-ment oned and other features of the invention will be better understood from the following description'of oneel'nbodiment of the invention taken inconnection with the drawingrepresenting those partsof'tlie machine necessary for the understanding ef the invent on. Q In the drawings, v v

v Fig. '1' is a view in perspective offparts of a last lathe embodying the invention, and

" Fig. 2 is a diagrammaticprojection,from the side, of the parts shown in Fig. 1,.

v The machine shown is a he lathe of ordii nary construction such as for example, is

shownin; United States Lat'ters Patent No. 5,4 1,891, granted August 20,1895 to W F. Gilman; Onl'yso' much of the machine is shown as tion The frame of the machineis. indicated atIQ. The pivots of a vprimary swing frame l l are indicated at; 12i12. I The spindles of the is material to the present. in'v'en' model and work, a last block, which margin the frame 14 are represented at :16 and are driven by any desired train of gearing 18- 20v22from thecenter 12,vthe pivotal axis in the frame; I The gear 22is integral with the:

and canibe regardedas m-ode'l 'drivingydog the model itself. V a

A secondary swing frame 24 is pivoted on the spindle axis. 16 and isl connected to the mainframe of'the machine'at 26 by'a sliding connection showntas a pin-and-slot connection 28, the axis of :the slot passing" through the axis16. This construction permits the swinging of both swingframes 14; and 24.

The cutter and model wheel centers are represented the points 30, 32 respectively, and

the grading .plane is 1630" 32.

In the embodi entof the invention disclosed, the centers 16, 28 and 30 are all equidistant from the center 12, and consequently V the block and driven by a gear 38'mounted on it, which meshes with the gear 22. For driving the block, the transmission gear. comprises an idler 40 which can be inserted at, or

will between a gear 42 like the gear 38 mounted on the shaft 36, and a gear 44 like the gear 22 mounted on the block spindle 16, 1n order to effect reverse drive. In Fig. 1 the gears are thus shownr For direct drive the gear 40 is removed and the gears 42 44 are engaged.

" It is clear that as the model rotates the swing frames 14 and 24 swing inand out corresponding to irregularities in the model sur face," and the grading plane 1630+32 moves asjtheaxis 16 swings about the center 12. It will now be shown that the secondary swingframe 24contains a plane which'will always be coincident with the grading plane, or, in other words, that the orientation of the secondary swing frame24 relativelyto the grading plane rema ns unaltered; This being assumed forthe present, it will be clear that if the reversing gearing in the secondary swing frame be arranged to rotate the model and block equally relatively to this fixed plane the'model and block will always be sym metrically located relatively to the grading plane,"as is desired.'

Returning now 'to Fig. 2, consider the effect of rotating the primary swing frame 14 about the center 12. This will cause the axis 16 to move around the circle 301 6-26, and the slot 28'will slide correspondingly on the pivot 26. The angle 26"16-30formed by the lines 16 -26 and 16'-30," being always measured by one-half the arc 26-3O on the circle 34, remains unchanged in value, and the line l6-80 ca n therefore be regardedas fixed to the secondary frame 24. This line '1630 can thus be regardedas defining a plane fixed in the secondary swing frame '24 "(and moving with it) whichalways passes through the axis 16 and the axes 30, 32', and therefore coincides with the grading plane, irrespective of swing frame rotation.

Now suppose for the moment that the mechanical drive is stopped, and theswing frame rotated through a certain angle. This I willin general cause a rotation of the gear 22 (which also represents th'e'model) relatively to the system 2416''30 which has just been provided to be integral. The two gears 38 and 42 and the reversing idler 40 being mounted in'this system will cause an exactly equal and opposite rotation of the block-gear 44 with regard to the system 24- 1630aboutthe center 16', whichis in the grading plane. The model and block have thus been'rotated equally in opposite directions from the grading plane 16-3032, and accurate right and left reproduction results. Clearly the continuous operation of the mechanical drive does not affect this condition in any way.

, a In the above-described embodiment of the invention, reverse cutting is effected by reversing the rotation of the block. It can also be obtained by reversing the rotationof the model, and nothing in the theory is-altered by this change in procedure. It is onlygneces sary that the reversing gearing be mounted on a member having an invariable plane always coincident with 'the grading plane. I In order to simplifythe wording of the above ,spectification and of the appended claims Ihave described the relations of the parts as seen in Fig. 2 which is an orthogonal projection of the parts asseen from the end of themachine. Having described myinvention, what claim "as new and desire to secure by Letters Patent ofthe UnitedSta-tesimf r 1 1.' In a copying lathfe, a'model wheel'anda cutter, a swing frame iarranged to carry a model and a block and pivoted on the main frame ofth e machine, and asecond swinging member carrying reversing gearing between 'the'model' and the block, said second swinging member being pivoted on the swing frame and having a pivotedsliding connection with the main frame of the machine, the pivot of said sliding connection, the pivotal'connection between the swing frame and the second. swinging member, and the center of the model wheel all being. equidistant fromfltlie pivotal connection of the swing frame with the main frame.

2 Ina copying lathe, a model wheel and a cutter, swing frame arranged 'to' carry a model and a block and pivoted on the main frame ofthe machine, and second. swinging member, pivoted on the swing frame and having a sliding pivotal connection with the main frame of the machine, the a-Xis or the slide passing through the pivotal connection between the swing frame and the second sw nging member, a gear mounted in the swing frame on the model axis and driven from the pivotal axis of the swing frame, a gear train driven by the first-mentioned gear and comprising .a reversing gear mounted in the second' swinging member, and a gear mounted' in the swing frame on the block axis and driven from the gear train, the pivotal axis of the swing frame being equidis tant from the model wheel axis the pivotal connection between the swing frame and the second swinging member, and the said sliding pivotal connection,

3. In a copying lathe, a model wheel and a cutter, a swing frame arranged to carry a'modeland' a blOCkflnd pivoted on the main frame of'themachine, and a second swinging member pivoted on theswing frame and having a sliding pivotal connection with the mainframe of the machine located on the frame at a substantial distance from the grading plane, the axis of the slide passing through the pivotal connection between the swing frame and the second swing member, a gear mounted in the, swing frame on the model axis and driven from the pivotal axis of the swing frame, a gear train driven by the first-mentioned gear and comprising a reversing gear mounted in the second swinging member, and a gear mounted in the swing frame on the block axis and driven from the gear train, the pivotalaxis of the swing frame being equidistant from the model wheel axis, the pivotal connection between the swing frame and the second swinging member, and the said sliding pivotal con- 7 nection. In testimony whereof I have signed my name to this specification.

LAURENCE E. TOPHAM. 

